System and method for radar disambiguation techniques

ABSTRACT

A system having an array of antennas with particular weights for signals associated with different groups of antennas. The array of antennas includes a first group of antennas positioned in a middle portion of the array of antennas, a second group of antennas positions at one or more edges of the array of antennas, and a third group of antennas positioned at one or more corners of the array of antennas. The system includes a control module configured to control each respective and tenant in the array of antennas. The control module can further be configured to weight the first group of antennas a first weighting amount, to weight the second group of antennas a second weighting amount and to weight the third group of antennas a third weighting amount. The weighting improves the system&#39;s ability to reduce ambiguities in an angle of arrival associated with the object.

PRIORITY

The present application is a continuation of U.S. patent applicationSer. No. 16/589,654, filed Oct. 1, 2019, which claims priority to U.S.Provisional Application No. 62/739,646, filed Oct. 1, 2018, and U.S.Provisional Application No. 62/788,353, filed Jan. 4, 2019, the contentsof which are herein incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to radar identification techniquesthrough the use of a multi-channel array design and applied weighting ina particular pattern in the array to produce data that reduces oreliminates ambiguity with respect to the angle of arrival of a receivedsignal.

BACKGROUND

Although radar technology has long existed, the radio signals producedthrough radar technology can vary in terms of clarity and completeness.The use of multiple antennas can magnify the range of radar imagery,however, it adds to the problems associated with signal ambiguity.System having an antenna array often use an equal weighting associatedwith each element in the array. In this scenario, a problem can arisewhere there is no unique answer with respect to an angle of arrival of asignal from the target object. A targeted object may appear in the dataas coming from a number of indeterminable radar angles. Identifying thetrue angle of arrival and thus the actual location of the object can bedifficult. The number of different angles in the data occurs because afirst side lobe of the received signal, a main lobe, and a second sidelobe can each have a respective angle of arrival. Therefore, there couldbe multiple answers regarding where the target object actually is whichcan be confusing or impossible to disambiguate.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otheradvantages and features of the disclosure can be obtained, a moreparticular description of the principles briefly described above will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. Understanding that these drawingsdepict only exemplary embodiments of the disclosure and are nottherefore to be considered to be limiting of its scope, the principlesherein are described and explained with additional specificity anddetail through the use of the accompanying drawings in which:

FIG. 1 illustrates an example system configuration;

FIG. 2A illustrates an example array of antennas;

FIG. 2B illustrates an example 3×3 array of antennas;

FIG. 3 illustrates an alternate array configuration of antennas;

FIG. 4 illustrates a shape of an array configuration of antennas;

FIG. 5 illustrates an alternate shape of an array configuration ofantennas;

FIG. 6 illustrates an alternate array configuration of antennas;

FIG. 7 illustrates an alternate shape of an array configuration ofantennas;

FIG. 8 illustrates an example weighting effect;

FIG. 9A illustrates gain versus angle of arrival for weighted andunweighted signals;

FIG. 9B illustrates a channel phase difference versus angle of arrivalfor weighted and unweighted signals;

FIG. 9C illustrates gain versus angle of arrival for weighted versusunweighted signals;

FIG. 9D illustrates channel phase difference versus angle of arrival forweighted and unweighted signals;

FIG. 9E illustrates an example method; and

FIG. 10 illustrates another example method

DESCRIPTION OF EXAMPLE EMBODIMENTS

Various embodiments of the disclosure are discussed in detail below.While specific implementations are discussed, it should be understoodthat this is done for illustration purposes only. A person skilled inthe relevant art will recognize that other components and configurationsmay be used without parting from the spirit and scope of the disclosure.

Overview

Additional features and advantages of the disclosure will be set forthin the description which follows, and in part will be obvious from thedescription, or can be learned by practice of the herein disclosedprinciples. The features and advantages of the disclosure can berealized and obtained by means of the instruments and combinationsparticularly pointed out in the appended claims. These and otherfeatures of the disclosure will become more fully apparent from thefollowing description and appended claims, or can be learned by thepractice of the principles set forth herein.

The present disclosure introduces technology which reduces or eliminatesthe possibility of having multiple objects identified in signalsreturned from a radar transmission. A radar system implementing thetechniques disclosed herein can produce a unique angle related to atarget relative to an antenna array. Weighting the elements in anantenna array according to a certain pattern can cause, in the analysisof the channel phase difference of a received signal from the targetobject, the signal indicating an angle of arrival that is associatedwith respective side lobes of the received signal to be shifted suchthat only a single signal associated with the main lobe can be used toidentify the angle of arrival. By effectively eliminating the side lobesignals, the system can disambiguate what the angle of arrival is forthe target object.

Disclosed is system and method of implementing an array of antennashaving particular weights for signals associated different groups ofantennas. An example system includes an array of antennas, the array ofantennas including a first group of antennas positioned in a middleportion of the array of antennas, a second group of antennas positionsat one or more edges of the array of antennas, and a third group ofantennas positioned at one or more corners of the array of antennas. Thesystem includes a control module (optional) configured to control eachrespective and tenant in the array of antennas. In one aspect, nocontrol module is used, and each element is constructed with itsrespective weight to cause the disambiguation approach disclosed herein.The control module, or the antenna elements, can be further configuredto define a first channel and can include at least a first antenna and asecond antenna. The first antenna and the second antenna can each be indifferent groups of antennas in the array of antennas. The controlmodule, or the antenna elements, can further be configured to weight thefirst group of antennas a first amount, to weight the second group ofantennas a second amount and to weight the third group of antennas athird amount. In one aspect, the first weighting amount is greater thanthe second weighting amount, and the second weighting amount is greaterthan the third weighting amount.

In one aspect, the first group of antennas includes between 1 and 5antennas, wherein the second group of antennas includes between 1 and 5antennas and wherein the third group of antennas includes between 1 and4 antennas. The array can be configured in a square shape, a rectangularshape, a circular shape or an oval shape. Generally the shapes aresymmetrical but other, even asymmetrical shapes, are considered.

An example method can include operating an array of antennas. The arrayof antennas can include a first group of antennas positioned in a middleportion of the array of antennas, a second group of antennas positionsat one or more edges of the array of antennas, and a third group ofantennas positioned at one or more corners of the array of antennas. Themethod includes defining a first channel of at least a first antenna anda second antenna, wherein the first antenna and the second antenna areeach in different groups of antennas in the array of antennas. Themethod can also include weighting a first group of signals associatedwith the first group of antennas a first weighting amount, weighting asecond group of signals associated with the second group of antennas asecond weighting amount and weighting a third group of signalsassociated with the third group of antennas a third weighting amount.The first amount is greater than the second amount, which is greaterthan the third amount.

The weighting of the antenna elements as described herein causes achannel phase difference versus angle of arrival of the signal receivedfrom a target object to only have a single available angle of arrivalassociated with the main lobe signal. The side lobe signals, which wouldindicate alternate angles of arrival in an unweighted scenario,disappear in a certain range of data, and thus eliminate the possibilityof an ambiguous angle of arrival for the signal.

DETAILED DESCRIPTION

The present disclosure addresses the issues raised above. The disclosureprovides a system, method and computer-readable storage deviceembodiments.

First a general example system shall be disclosed in FIG. 1, which canprovide some basic hardware components making up a server, node or othercomputer system. FIG. 1 illustrates a computing system architecture 100wherein the components of the system are in electrical communicationwith each other using a connector 105. Exemplary system 100 includes aprocessing unit (CPU or processor) 110 and a system connector 105 thatcouples various system components including the system memory 115, suchas read only memory (ROM) 120 and random access memory (RAM) 125, to theprocessor 110. The system 100 can include a cache of high-speed memoryconnected directly with, in close proximity to, or integrated as part ofthe processor 110. The system 100 can copy data from the memory 115and/or the storage device 130 to the cache 112 for quick access by theprocessor 110. In this way, the cache can provide a performance boostthat avoids processor 110 delays while waiting for data. These and othermodules/services can control or be configured to control the processor110 to perform various actions. Other system memory 115 may be availablefor use as well. The memory 115 can include multiple different types ofmemory with different The processor 110 can include any general purposeprocessor and a hardware module or software module/service, such asservice 1 132, service 2 134, and service 3 136 stored in storage device130, configured to control the processor 110 as well as aspecial-purpose processor where software instructions are incorporatedinto the actual processor design. The processor 110 may be aself-contained computing system, for example, containing multiple coresor processors, a bus (connector), memory controller, cache, etc. Amulti-core processor may be symmetric or asymmetric.

To enable user interaction with the computing device 100, an inputdevice 145 can represent a variety of input mechanisms, such as amicrophone for speech, a touch-sensitive screen for gesture or graphicalinput, a keyboard and/or mouse, e.g., for motion input and so forth. Anoutput device 135 can also be one or more of a number of outputmechanisms known to those of skill in the art. In some instances,multimodal systems can enable a user to provide multiple types of inputto communicate with the computing device 100. The communicationsinterface 140 can generally govern and manage the user input and systemoutput. There is no restriction on operating on any particular hardwarearrangement and therefore the basic features here may easily besubstituted for improved hardware or firmware arrangements as they aredeveloped.

Storage device 130 is a non-volatile memory and can be a hard disk orother types of computer readable media which can store data that areaccessible by a computer, such as magnetic cassettes, flash memorycards, solid state memory devices, digital versatile disks, cartridges,random access memories (RAMs) 125, read only memory (ROM) 120, and/orhybrids thereof.

The storage device 130 can include software services 132, 134, 136 forcontrolling the processor 110. Other hardware or softwaremodules/services are contemplated. The storage device 130 can beconnected to the system connector 105. In one aspect, a hardware modulethat performs a particular function can include the software componentstored in a computer-readable medium in connection with the necessaryhardware components, such as the processor 110, connector 105, display135, and so forth, to carry out the function.

One of the common problems with antenna theory results when a replica ofa transmitted image is offset from the actual position. Ambiguitiesexist when unweighted antenna arrays transmit a radar signal, which isreflected off a target object. In some detection systems, signalsrelated to a main lobe of the signal as well as side lobes of the signalcan cause a detection system to identify multiple different angles ofarrival for that signal. One angle of arrival can be associated with themain lobe, and other angles of arrival can be associated with respectiveside lobes. This can be confusing and indeterminate with respect to theangle of arrival of the signal and thus cause confusion with respect tothe actual location of the object. Typically, antenna designers seek toimplement a better antenna or cable system to mitigate the impact ofambiguities. As disclosed herein, the novel approach involves weightingsignals at individual antennas in a particular way which can impact thesignals associated with each channel in a particular way. This shall bedescribed in more detail below.

FIG. 2A illustrates a basic array of antennas as disclosed herein.Disclosed is system and method of implementing an array of antennas 200having particular weights for signals associated with different groupsof antennas. A set of antennas 202, 204, 206, 208, 210, 212, 214, 216,218, 220, 222, 224, 226, 228, 230, and 232 can include antennas ofvarious specifications and types. The array of antennas can include afirst group of antennas positioned in a middle portion of the array ofantennas. The first group of antennas, by way of example, can includeone or more of antennas 212, 214, 220, 222. A second group of antennascan be positioned at one or more edges of the array of antennas. Forexample, the second group of antennas can include one or more ofantennas 204, 206, 216, 224, 228, 230, 210 and 218. A third group ofantennas can be positioned at one or more corners of the array ofantennas. An example of the third group of antennas can include any oneor more of antennas 202, 208, 232 and 226. Each antenna and the array ofantennas 200 can communicate with a control module 234.

An example antenna is used herein and can include a patch antenna, whichis a type of radio antenna having a low profile, in which it can bemounted on a flat surface. A patch antenna consists of a flatrectangular sheet or patch of metal mounted over a larger sheet of metalcalled a ground plane. The two metal sheets together form a resonantpiece of microstrip transmission line with a length approximately onehalf of the wavelength of the radio waves. The radiation mechanismarises from discontinuities at each truncated edge of the microstriptransmission line. The radiation at the edges causes the antenna to actslightly larger electrically than its physical dimensions. In order forthe antenna to be resonant, a length of microstrip transmission lineslightly shorter than one-half a wavelength at the frequency is used.

In one example, multiple patch antennas can be configured on a samesubstrate, and can be called microstrip antennas. These can be used tomake high gain array antennas and phased arrays in which the beam can beelectronically steered. The particular structure of the antenna can bevaried in this disclosure. However, a preferred antenna type is thepatch antenna as an array of patch antennas can be used in variouscontexts such as on a drone which can be deployed to identify objects inairspace. The principles disclosed herein can apply to any type ofantennas such as a bow-tie antenna, a dipole array, a monopole antenna,a loop antenna, a helical antenna, yagi-uda antenna, a planar inverted-Fantenna, a rectangular microstrip antenna, a corner reflector, aparabolic reflector, and so forth

A control module may be used to control the weighting of the antennas.The control module 234 can be configured to control each respectiveantenna in the array of antennas 200. The control module 234 can befurther configured to define a first channel to include at least a firstantenna and a second antenna. The first antenna and the second antennacan each be in different groups of antennas in the array of antennas.For example, the first channel can be defined by the signals transmittedand/or received by antennas 206 and 214. In this regard, signal 214could be considered within the first group of interior antennas andantenna 206 can be an edge antenna. The channel may also be defined bymore than 2 antennas. For example, a first channel 236 can be defined bythe signals transmitted and/or received by antennas 202, 204, 210, and212. Similarly, a second channel 238 could be defined by the signalstransmitted and/or received from one or more of antennas 206, 208, 214,and 216. A third channel 240 can be defined by one or more of theantennas 222, 224, 230 and 232. A fourth channel 242 could be defined byone or more of the signals transmitted and/or received from antennas218, 220, 226 and 228. Indeed, a channel can be defined in the contextof this disclosure by any one or more antennas in the array of antennas.It also is not a requirement that antennas used to define a channel arecontiguous. However, in a preferred aspect of this disclosure, wheremore than one antenna is utilized to define a channel, the weighting ofthe more than one antenna will differ so as to result in the improvedsignal processing that is described herein. By weighting the antennas inthe particular positions as described herein, the resulting signalprocessing improves the ability of the system to identify objects andavoid ambiguity issues.

As noted above, in one aspect, no control module is needed for weightingbecause the physical structure of the antennas in the antenna array canbe configured to build into the antenna the desired weighting. Bothapproaches can apply.

The control module, or the structure of the antennas, can further beconfigured to weight the first group of antennas a first weightingamount, to weight the second group of antennas a second weighting amountand to weight the third group of antennas a third weighting amount. Inone aspect, the first weighting amount is greater than the secondweighting amount, and the second weighting amount is greater than thethird weighting amount. An example weighting can include a firstweighing amount between −1 and 1 dB, a second weighting amount between−6 and −4 dB, and a third weighting amount between −9 and −11 dB. In anexample scenario, the antennas within this defined first channel caninclude antenna 214 with the first weighting amount and antenna 206 withthe second weighting amount. For example, antenna 214 can be weighted at0 dB and antenna 206 can be weighted at around −5 dB. Where the secondchannel 238 is defined by antennas 206, 208, 214 and 216, exampleweighting for that channel can be antenna 214 at 0 dB, antennas 206, 216at approximately −5 dB and a third antenna 208 at −10 dB. A similarstructure can also be implemented for the third channel 240 by havingantenna 222 weighted at 0 dB, antennas 224, 230 weighted at −5 dB andantenna 232 weighted at −10 dB. Any identification of the waiting amountis approximate and can vary up or down at least several dB. All of theweightings disclosed herein are by way of example and any range can beimplemented, including in an inverse order of magnitude from what isdescribed herein.

In one aspect, the first group of antennas includes between 1 and 5antennas, wherein the second group of antennas includes between 1 and 5antennas and wherein the third group of antennas includes between 1 and4 antennas. In one aspect, the array of radar antennas includes MxNantennas, where M can be between 3 and 7 and N can also be between 3 and7. In one example array, M=4 and N=4. The array can be configured intovarious shapes, a few examples of which will be described below. On a5×5 sized array, for example, one could have five different weightingschemes.

The combination of elements or antennas in the array that define anindividual channel can depend on the number of elements and/or theconfiguration. For example, where a 3×3 element array 250 is used as isshown in FIG. 2B, a center element 252 might have a splitter associatedwith it, such that its signal is communicated to 4 individual channelsas shown. Edge elements 254, 256, 258, 260 can include splitters thesplit each respective signal in half as shown. In this manner, a 9element array can produce four channels for signal processing. A firstchannel can be defined by elements 262, 254 (cut in half), 252 (cut in afourth), and 260 (cut in half). A second channel can be defined byelements 264, 256 (cut in half), 252 (cut in a fourth), in 254 (cut inhalf). A third channel can be defined by elements 266, 258 (cut inhalf), 252 (cut in a fourth), and 256 (cut in half). Finally, a fourthchannel can be defined by elements 268, 260 (cut in half), 252 (cut in afourth), and 258 (cut in half). The weighting associated with theseelements can include, for example, a 0 dB weight on element 252, a −5 dBweight on elements 254, 256, 258 and 260 and a −10 dB weight on elements262, 264, 266, 268.

The fact that splitters are involved in splitting signals from elementsto define the respective channels can impact the weight for anyrespective channel. For example, the weighting of the signal fromelement 252 may be impacted with respect to each channel given that thesignal is split by the splitter. For example, a 0 dB element 252, splitinto 4 different signals, my, cause a channel defined by elements 252,254, 250, 256 to view the signal from element 252 as having a −6 dBweight. However, after signal processing, the values can be added backtogether to address this issue. In one aspect, using splitters is shownin FIG. 2B maintains a symmetric nature of each respective channelrelative to the physical configuration of elements in the array.

The process of disambiguation can use these various channels asdescribed herein. For example, signals from the respective channels thatare in phase or out of phase can impact whether those signals arerepresentative of signals from a main lobe or a side lobe of thereceived signal. FIGS. 9A-9D illustrate the relationship between thegain versus angle of arrival of a signal received from a target objectand a channel phase difference versus the angle of arrival with respectto the main lobe or side lobes. The presentations in the various antennaconfigurations help to identify and understand how various channels aredefined by groups of elements in different antenna configurations, howthose elements are weighted (either through a control module or theconstruction of each element), and how the comparison of phases betweenthe different channels with respect to angle of arrival of a receivedsignal from the target object can be utilized to determine ordisambiguate the angle of arrival. Different antenna arrayconfigurations can provide varying constructs for defining differentchannels and can produce varying results with respect to a channel phasedifference utilizing weighted elements. However, the general idea thatrepresents the innovation disclosed herein involves weighting thedifferent elements so as to enable an identification of a single angleof arrival in a received signal that can be confirmed as beingassociated with the main lobe of the received signal because thepossible side lobe components would be eliminated by virtue of theweighting of the elements. Again, this feature will become more clearwith the description of FIGS. 9A-9D below.

FIG. 3 illustrates antennas 300, which are configured with the first rowof antennas 302, 304, 306, 308 and 310, a second row of antennas 312,314, 316, 318, 320 and 322 and a third row of antennas 324, 326, 328,330 and 332. Each antenna communicates with a control module 334, when acontrol module is used. In this regard, central antennas can be weightedwith a first amount as described herein. The central antennas could beone or more of antennas 314, 316, 318, 320. Edge antennas could includeone or more of antennas 304, 306, 308, 326, 328, 330, 312, 322. Thesecould be assigned a separate weight as described herein. A third groupof corner antennas can include one or more of antenna 302, 310, 312,322, 324 and 332. Any two or more of the antennas in the array 300 canbe combined to define a respective channel.

FIG. 4 shows an outlined perimeter 402 around the array of antennas 400to depict that the resulting shape is that of an oval. Other shapes,such as a square shape, a rectangular shape, a circular shape, and soforth, can be considered as well. Both symmetric and asymmetric shapesare included within this disclosure. FIG. 5 shows an antenna array 500with a trapezoidal shaped perimeter 502 emphasizing that the shapes ofan antenna array can include non-symmetric as well as symmetricstructures.

It is preferable that the two or more antennas that are confined todefine a channel would have different weights. In one example, wherethree or more antennas are combined to define a channel, there can be atleast three different weights respectively applied to each separateantenna. Furthermore, it is contemplated that the antennas may bedivided into two different weight groups or more than three weightsamongst the antennas. For example, fine-tuning could occur in whichfour, five, six or more weights are distributed amongst interior, edgeand corner antennas. It is generally contemplated that higher dB valuesare assigned to interior antennas, midrange dB values are assigned toedge antennas and lower range values are assigned to corner antennas.However, the inverse may be applied as well.

The array of radar antennas in the overall shape of the array caninclude between 12 and 18 antennas in at least 4 rows. The array ofradar antennas can include a first row having three antennas, a secondrow having four antennas, a third row having five antennas, and a fourthrow having four antennas. For example, FIG. 6 illustrates an array 600including antennas 602, 604, 606, 608, 610, 612, 614, 616, 618, 620,622, 624, 626, 628, 630 and 632. Each antenna can indicate with acontrol module 634. The antenna array 600 is set on its side in thesense in this figure. If one were to view the antenna in a morehorizontal fashion, a first row of antennas could be defined by antennas602, 608, and 616. A second row of antennas can include antennas 604,610, 618 and 624. A third row of antennas can include antennas 606, 612,620, 626, and 630. A bottom row of antennas can include antennas 614,622, 628, and 632. The spacing and configuration of the antennas definesa certain shape which is hexagonal in nature, but more complicated. FIG.7 illustrates the antenna array 700 outlined with a perimeter 702 whichgives a more clear definition of the hexagonal shape.

Again, in this scenario, the concepts disclosed herein involve weightingsignals associated with different groups of antennas that definedifferent channels. For example, a first weight in the array 600 can beassigned to interior antennas 610, 612, 618, 620 and 626. A second groupof antennas can be assigned the second weight. In this example, thesecond group can include one or more of antennas 604, 622, 628, 624, and608. A third group can include one or more of antennas 602, 606, 614,632, 630 and 616. Higher weights can be assigned to the first group,midrange weighting can be assigned to the second group and lower rangeweighting can be assigned to the third group.

The groups described herein are just example configurations and anycombination of weighting can be applied to any shape of an antennaarray. Any two or more different weighting schemes can be applied. Inone scenario, a first channel can be defined by antennas 602, 604, 608and 610. In this scenario, antenna 610 can be assigned approximately aweight of 0 dB, antennas 604 and 608 can be assigned a midrange weightof −5 dB and corner antenna 602 can be assigned a low range weight of−10 dB.

The weighting assignments, of course, can vary and are not meant to beexact dB amounts. For example, the first amount can include between −2and 2 dB, the second amount can be between −8 and −2 dB and the thirdamount can be between −7 and −13 dB. The weighting could be expandedtoo, for example, the first amount can be between −5 and 5 dB, thesecond amount can be between −10 and 10 dB and the third amount can bebetween −20 and 20 dB. Other ranges are contemplated as well.

In one example, an array of radars can be deployed on a building or on amobile device such as a drone. The unit can be defined well with two ormore antenna arrays used for identifying objects. When an object isidentified in the field of view of these radar arrays, the controlmodule or other processing technology can stitch together the varioussignals from the separate antennas and identify a single object. This isa difficult process. One challenge is identifying the angle of arrivalof an incoming signal which, if identified, enables the system toidentify a latitude and longitude for the object as well as how far theobject is above the ground. This type of information can prove to behighly valuable.

Having 4 antennas alone in a row or as part of an array results inambiguity at different angles. The system may not know if a target isfrom one angle or another. By applying a weighting across the pluralityof antennas, a phase vs. angle response is created. The phase is thedifference between the two antennas and a non-uniqueness result. Thenon-uniqueness result can occur with any two antennas within the array.

As mentioned, in order to improve the signal pattern, a weightingfunction can be used. Weighting of the radar signal can occur in thetransmission of the signal, the receiving of the signal or both thetransmission and receiving of the signal, but typically occurs duringthe receiving of the signal. Various weighting methods can be employedand options include a Hamming weighting, Blackmann weighting, a Taylorweighting, and so forth.

In some instances, a weighting function can change the distribution ofthe amplitude and phase of a signal that is received, namely the beamwidth and the level of the side lobes. Usually decreasing the beam widthis accompanied by increasing the side lobes level. For example, a lowbeam width and a low level of side lobes are usually two contradictoryrequests for any antenna array. If one decreases, the other increases,so a balance between the two has to be made for each specificapplication.

FIG. 8 shows a weighting effect on a generic signal. A generic weightingcomparison graph 800 shows an unweighted signal represented by a solidline 802, and a weighted signal represented by a dashed line 804. Theunweighted signal 802 includes unweighted peak side lobe levels 806 thatare larger dB when compare to the peak side lobe levels of the weightedsignal 808. However, the weighted signal 804 also shows that the mainlobe width is larger than the main lobe width of the unweighted signal802, which results in a degraded resolution of the weighted signal 804.Ideally, a preferred weighting is realized when reducing the level ofthe side lobes is achieved with a minimal sacrifice to the signal'sresolution.

In one aspect, the weighting of signals can be described as a weakweighting or a strong weighting. For example, a weak weighting can be−10 dB or −5 dB and strong weighting can be 0 dB. The patch antennasrespectively combine and form a channel, as defined herein, and thetarget in the field of view will produce a received signal. The systemcan perform signal processing and use a phase difference between the twosignals to identify where the target is. Typically, this disclosureincludes the concept of including a weak weighting and a strongweighting within each channel.

FIG. 2 shows a full array of 4×4 patch antennas, horizontally andvertically. The weighting approach disclosed herein reduces the amountof ambiguity. Ambiguities can result in both a horizontal direction andin the vertical direction. In one example, there can be 4 channels and aweighting in each direction. The middle antennas are weighted thestrongest and the weighting of antennas tapers to the outside of thearray.

Part of the reason why the weighting approach disclosed herein issuccessful is because by weighting the antennas, the system moves thephase centers closer together which results in a phase difference. Thephase difference between the two channels is the relationship betweenthe left and the right side. The slope of the phase changes in thecenter and the nature of a fast Fourier transform (FFT) window reducethe side lobes. The difference of the two channels is can result inhaving one channel that dominates. The two side lobes are going to lookhigh, but will be out of phase. The channels will have high side lobes,but because their amplitudes are so different, they cancel each otherout and the total array results in a phase that is no longer linearwrapping. This process applies the theory of windowing and tapering inthe spatial domain and reduces the side lobes. A mathematical fact isthat the difference between the two halves is going to have high sidelobes and cause the phase to be out of phase. The resulting sum is lowbecause they are out of phase.

The antenna arrays disclosed herein are steerable, but the results arethe same whether you are steering in foresight or off axis. The phaseand side lobe relationship is consistent. Without the taper, the systemwould have a linear phase response that wraps and probably starts fromthe middle and goes to the edges. This is the ambiguity problem where inconstant phase it is impossible to determine the angle or phase. Bytapering the high regions that are out of phase, the +180 and −180°slightly weaken the slope and the phase centers are closer together.When it wraps it tends to smooth out and stay closer to 180° which iswhere the out of phase comes from. The degree that it works is dependenton the weighting that is used. More weighting is better, but the systemresults in some disadvantages such as the slope decreasing and someextra gain. The preferred weighting is in the range of 4-6 dB, but theweighting choice can depend on one or more parameters such as theapplication, an accuracy of the manufacturing irregularities and adesire to maximize the gain or high angle accuracy. For example, thesystem can sacrifice some high angle and gain by increasing theweighting, which results in more robustness against irregularities likeexternal effects or manufacturing tolerances. Increasing the weightingalso increases the field of view.

FIGS. 9A-9D show the phase difference versus angle of arrival for anarray steered to boresight (0°) in FIG. 9B and to 30° from boresight inFIG. 9D. FIGS. 9A-9D illustrate how the angle can be unambiguouslymeasured using the phase difference for two steering angles, zerodegrees shown in FIG. 9A and FIG. 9B and 30° illustrated by FIG. 9C andFIG. 9D. An example array is divided into a 2×2 array of 4 channels,where each channel is composed of a number of weighted and steerableelements. The elements can be symmetrically weighted about horizontaland vertical lines that pass through the center of the array. In oneexample, the weighting is applied in both the horizontal and verticaldirections. Additionally, the elements can be steered in a particulardirection by applying a progressive phase shift across the elements inthe array. The weighted and phase-shifted output of the elements foreach channel is then combined coherently to produce the channel outputfor the 4 channels.

When a signal from a particular direction impinges on the array, thesystem measures the horizontal angle of arrival by coherently combiningthe left two channels, and coherently combining the right two channels,and then measures a coherent phase difference between these combinedchannels. The system measures the vertical angle of arrival bycoherently combining the top two channels, and coherently combining thebottom two channels. The system then measures the coherent phasedifference between these combined channels. The measurement of thechannel phase difference versus angle of arrival is shown in FIGS. 9Band 9D.

When an equally weighed array is used, signals from the main lobe andmultiple side lobes produce the same phase. This is shown by the signal904 in the graph 900 of FIG. 9A, the signal 914 in the graph 910 of FIG.9B, the signal 924 in the graph 920 of FIG. 9C and the signal 934 in thegraph 930 FIG. 9D. However, when a suitably weighted antenna is used,the phase difference will be close to out-of-phase in the side lobes.Signal 902 in FIG. 9A represents the gain versus angle of arrival for aweighted antenna steered to 0°. Signal 922 in the graph 920 of FIG. 9Crepresents the gain versus angle of arrival for a weighted antennasteered to 30°. Signal 932 in the graph 930 of FIG. 9D represents thechannel phase difference versus angle of arrival for a weighted antennasteered to 30°. As shown in FIG. 9D, the point 936 represents themaximum unambiguous angle for a weighted antenna. Signal 912 in graph910 of FIG. 9B represents the channel phase difference versus angle ofarrival for the weighted antenna steered to 0°. The phase difference inthe main lobe will span all values from −180° to 180°. If the measuredphase difference shown in FIG. 9B falls in a certain range, then thesystem can unambiguously determine the impinging signal's angle ofarrival along the axis that is being measured. For an antenna steered tozero degrees, see FIG. 9B for the maximum unambiguous angle for theweighted antenna at point 916.

Feature 906 represents the main lobe and feature 908 represents the sidelobes in FIG. 9A. Feature 926 represents the main lobe and feature 928represents the side lobes in FIG. 9C.

Note in FIG. 9B that the unweighted phase difference 915 and 911 canrepresent signals which can be ambiguous with respect to the angle ofarrival. For example, at a phase difference of 50°, the angle of arrivalcould be −60° (signal 915) or about 8° (signal 914) as shown in FIG. 9B.At a phase difference of −50°, the signal 914 could indicate that theobject is at an angle of about −8° or signal 911 might indicate that itis at 60°. The signal 915 can relate to a side lobe 908 left of the mainload 906 shown in FIG. 9A. The signal 911 can relate to the side lobe908 on the right side of the main lobe 906 shown in FIG. 9A.

When weighting is used as disclosed herein, the unweighted signal 915moves to the position shown by weighted signal 917. Signal 911 moves tothe position shown by weighted signal 913. As can be appreciated, withthe weighted signal, at a phase difference of 50°, the angle of arrivalis shown by signal 912 as 20° and there is no alternate signalassociated with side lobe region which can cause confusion. Signal 917has shifted as well as signal 913, only leaving a single option along acertain range between approximately −140 and 140° of phase difference.This is why feature 916 represents the maximum unambiguous angle for theweighted antenna. Above that phase difference, say at 155 or 160°, thesignal 917 can come into play and cause the result to be ambiguous.Therefore, in one aspect, the present disclosure addresses interpretingor reading the angle of arrival of a signal only within a range in whichonly a single solution is identified from the analysis.

A similar approach can also be applied to FIG. 9D in which theunweighted signal 940 shifts. Upon applying a weighting to the antennaarray to result in signal 942 and signal 944. This shift causes a singleresult embodied in signal 932 four. A phase difference betweenapproximately −140 and 140° as is shown in the figure. This is whyfeature 936 is represented as the maximum unambiguous angle for aweighted antenna array.

In one aspect, where a weighted antenna array results in multiplepotential angles of arrival for a target object, the method may includerepositioning the antenna array on a flying vehicle in order to positionthe antenna array such that the received signal is more likely to bewithin the proper range, which only yield a single result for the angleof arrival. In another aspect, the array can be electrically steeredrather than physically moved.

A lookup table or other suitable transformation can be used to determinethe angle of arrival from the measured phase difference in theunambiguous range. Measured phase differences that fall into anambiguous region can be labeled as side lobe signals that fall outsideof the central unambiguous part of the main lobe, where the angle ofarrival is otherwise unknown. Regions 918 and 920 in FIG. 9B representthe ambiguous regions. Region 938 in FIG. 9D represents the ambiguousregion.

FIG. 9E illustrates a method embodiment related to the conceptsdescribed above. An example method includes symmetrically weightingrespective elements in an antenna array, the respective elements beingcombinable to define a plurality of channels (950), transmitting arespective channel output for each channel of the plurality of channels(952), receiving, at the antenna array, a signal from an object inresponse to the transmitting of the respective channel output (954),measuring a horizontal angle of arrival by coherently combining a lefttwo channels of the plurality of channels and coherently combining aright two channels of the plurality of channels to yield first combinedchannels and measuring a first coherent phase difference between thefirst combined channels (956), measuring a vertical angle of arrival bycoherently combining a top two channels of the plurality of channels andcoherently combining a bottom two channels of the plurality of channelsto yield second combined channels and measuring a second coherent phasedifference between the second combined channels (958) and applying atransformation to the first coherent phase difference and the secondcoherence phase difference to yield an angle of arrival associated withthe signal from the object (960).

FIG. 10 illustrates a method example 1000 as disclosed herein. A methodincludes operating, via a control module or otherwise, an array ofantennas, the array of antennas including a first group of antennaspositioned in a middle portion of the array of antennas, a second groupof antennas positions at one or more edges of the array of antennas, anda third group of antennas positioned at one or more corners of the arrayof antennas (1002), defining, via the control module, a first channelcomprising at least a first antenna and a second antenna, wherein thefirst antenna and the second antenna are each in different groups ofantennas in the array of antennas (1004), weighing a first group ofsignals associated with the first group of antennas a first weightingamount (1006), weighting a second group of signals the second group ofantennas a second weighting amount (1008) and weighting a third group ofsignals the third group of antennas a third weighting amount (1010). Thereceived signals based on the weighting includes the essentialelimination of side lobe potential angle of arrival signals and thusonly leaves the main lobe data to determine more accurately andunambiguously what the angle of arrive is.

Other actions can also follow the features outlined in FIG. 10. Forexample, where an array of antennas is configured on a drone to identifyan object or location of an object, the process outlined in FIG. 10 canbe deployed and various weights can be applied to signals in order toarrive at an identification or classification of the object and itslocation. Once radar is used to determine the angle of arrival of asignal, which can then provide latitude and longitude for the object,the drone can queue a camera on the object and take yet further actionssuch as deploying a netting system to capture the object if it is a badactor. In this regard, the method can include utilizing a weightingscheme in an array of antenna elements such that interior elements areweighted more than exterior elements as described herein, identifying alatitude and longitude associated with an object in the field of view ofthe intent array and taking an action based on the latitude andlongitude associated with the object. The action can include pointing anoptical based device, such as a camera, at the object, as well asperforming other actions such as shooting a projectile at the object,capturing the object, deploying a net to capture the object, scramblinga signal associated with the object, reporting the object, organizingand deploying a swarm of multiple drones associated with controlling theobject, and so forth.

The above approach works well for single targets and typically isdesigned for a small array of antennas configured on a drone. Theweighting could vary for larger arrays or a larger number of channels,such as 16 channels and would also work for land-based, larger antennasarrays as well.

In some embodiments the computer-readable storage devices, mediums,and/or memories can include a cable or wireless signal containing a bitstream and the like. However, when mentioned, non-transitorycomputer-readable storage media expressly exclude media such as energy,carrier signals, electromagnetic waves, and signals per se.

Methods according to the above-described examples can be implementedusing computer-executable instructions that are stored or otherwiseavailable from computer readable media. Such instructions can include,for example, instructions and data which cause or otherwise configure ageneral purpose computer, special purpose computer, or special purposeprocessing device to perform a certain function or group of functions.Portions of computer resources used can be accessible over a network.The computer executable instructions may be, for example, binaries,intermediate format instructions such as assembly language, firmware, orsource code. Examples of computer-readable media that may be used tostore instructions, information used, and/or information created duringmethods according to described examples include magnetic or opticaldisks, flash memory, USB devices provided with non-volatile memory,networked storage devices, and so on.

Devices implementing methods according to these disclosures can includehardware, firmware and/or software, and can take any of a variety ofform factors. Typical examples of such form factors include laptops,smart phones, small form factor personal computers, personal digitalassistants, rackmount devices, standalone devices, and so on.Functionality described herein also can be embodied in peripherals oradd-in cards. Such functionality can also be implemented on a circuitboard among different chips or different processes executing in a singledevice, by way of further example.

The instructions, media for conveying such instructions, computingresources for executing them, and other structures for supporting suchcomputing resources are means for providing the functions described inthese disclosures.

Although a variety of examples and other information was used to explainaspects within the scope of the appended claims, no limitation of theclaims should be implied based on particular features or arrangements insuch examples, as one of ordinary skill would be able to use theseexamples to derive a wide variety of implementations. Further andalthough some subject matter may have been described in languagespecific to examples of structural features and/or method steps, it isto be understood that the subject matter defined in the appended claimsis not necessarily limited to these described features or acts. Forexample, such functionality can be distributed differently or performedin components other than those identified herein. Rather, the describedfeatures and steps are disclosed as examples of components of systemsand methods within the scope of the appended claims. Moreover, claimlanguage reciting “at least one of” a set indicates that one member ofthe set or multiple members of the set satisfy the claim.

It should be understood that features or configurations herein withreference to one embodiment or example can be implemented in, orcombined with, other embodiments or examples herein. That is, terms suchas “embodiment”, “variation”, “aspect”, “example”, “configuration”,“implementation”, “case”, and any other terms which may connote anembodiment, as used herein to describe specific features orconfigurations, are not intended to limit any of the associated featuresor configurations to a specific or separate embodiment or embodiments,and should not be interpreted to suggest that such features orconfigurations cannot be combined with features or configurationsdescribed with reference to other embodiments, variations, aspects,examples, configurations, implementations, cases, and so forth. In otherwords, features described herein with reference to a specific example(e.g., embodiment, variation, aspect, configuration, implementation,case, etc.) can be combined with features described with reference toanother example. Precisely, one of ordinary skill in the art willreadily recognize that the various embodiments or examples describedherein, and their associated features, can be combined with each other.

A phrase such as an “aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations. Aphrase such as an aspect may refer to one or more aspects and viceversa. A phrase such as a “configuration” does not imply that suchconfiguration is essential to the subject technology or that suchconfiguration applies to all configurations of the subject technology. Adisclosure relating to a configuration may apply to all configurations,or one or more configurations. A phrase such as a configuration mayrefer to one or more configurations and vice versa. The word “exemplary”is used herein to mean “serving as an example or illustration.” Anyaspect or design described herein as “exemplary” is not necessarily tobe construed as preferred or advantageous over other aspects or designs.

Moreover, claim language reciting “at least one of” a set indicates thatone member of the set or multiple members of the set satisfy the claim.For example, claim language reciting “at least one of A, B, and C” or“at least one of A, B, or C” means A alone, B alone, C alone, A and Btogether, A and C together, B and C together, or A, B and C together.

We claim:
 1. An antenna system comprising: a first group of antennas ata first position of an antenna array, wherein the first group ofantennas is weighted a first weighting amount; a second group ofantennas at a second position of the antenna array, wherein the secondgroup of antennas is weighted a second weighting amount; a third groupof antennas at a third position of the antenna array, wherein the thirdgroup of antennas is weighted a third weighting amount; and a firstantenna and a second antenna, wherein the first antenna and the secondantenna define a first channel, wherein the first antenna and the secondantenna are each in different groups of antennas in the antenna array.2. The antenna system of claim 1, wherein the first group of antennas ispositioned in a middle portion of the antenna array.
 3. The antennasystem of claim 1, wherein the second group of antennas is positioned atone or more edges of the antenna array.
 4. The antenna system of claim1, wherein the third group of antennas is positioned at one or morecorners of the antenna array.
 5. The antenna system of claim 1, whereina control module is configured to control the weighting of the antennas.6. The antenna system of claim 1, wherein a control module is configuredto control the weighting of the antennas is hard coded into eachantenna.
 7. The antenna system of claim 1, wherein the first group ofantennas comprises between 1 and 5 antennas, wherein the second group ofantennas comprises between 1 and 5 antennas and wherein the third groupof antennas comprises between 1 and 4 antennas.
 8. The antenna system ofclaim 1, wherein the antenna array comprises M×N antennas.
 9. Theantenna system of claim 8, wherein M=4 and N=4.
 10. The antenna systemof claim 1, wherein the antenna array is configured such that an overallshape of the antenna array comprises one of a square, a rectangle, acircle or an oval.
 11. The antenna system of claim 10, wherein theantenna array in the overall shape of the oval comprises between 12 and18 antennas in at least 4 rows.
 12. The antenna system of claim 1,wherein the antenna array comprises a first row having three antennas, asecond row having four antennas, a third row having five antennas, and afourth row having four antennas.
 13. The antenna system of claim 1,wherein the first weighting amount is greater than the second weightingamount, and wherein the second weighting amount is greater than thethird weighting amount.
 14. The antenna system of claim 13, wherein thefirst weighting amount comprises between −1 and 1 dB, the secondweighting amount comprises between −6 and −4 dB in the third weightingamount comprises between −9 and −11 dB.
 15. A method comprising:operating, via a control module, an array of antennas, the array ofantennas comprising a first group of antennas at a first position, asecond group of antennas positions at a second position, and a thirdgroup of antennas positioned at a third position; defining a firstchannel comprising at least a first antenna and a second antenna,wherein the first antenna and the second antenna are each in differentgroups of antennas in the array of antennas; weighting a first group ofsignals associated with the first group of antennas a first amount;weighting a second group of signals associated with the second group ofantennas a second amount; and weighting a third group of signalsassociated with the third group of antennas a third amount.
 16. Themethod of claim 15, further comprising, one or more of: wherein thefirst amount comprises between −1 and 1 dB, wherein the second amountcomprises between −4 and −6 dB and wherein the third amount comprisesbetween −9 and −11 dB.
 17. The method of claim 15, wherein the weightingof the first group of signals, the weighting of the second group ofsignals and the weighting of the third group of signal is controlled bythe control module.
 18. The method of claim 15, wherein the weighting ofthe first group of signals, the weighting of the second group of signalsand the weighting of the third group of signals are applied in both ahorizontal direction and a vertical direction.
 19. The method of claim15, wherein the first amount is greater than the second amount, andwherein the second amount is greater than the third amount.
 20. Themethod of claim 15, wherein the array of radar antennas is configuredsuch that an overall shape of the array of radar antennas comprises oneof a square, a rectangle, a circle or an oval.